Ammeter



Patented Feb. 23. 1932 uNlTED STATES PATENT olf-Fics 02|' SPRINGFIELD, NEW JERSEY, ABSIGNOB TQ ILAN"U'I'A(2- TUBING COMPANY, F NEWARK, NEW JERSEY Application illed November 1B, 1829. Serial lo. 407,903.

provide an ammeter composed of a minimum number of parts whereby the cost of manuy facture may be greatly reduced.

Another object of my invention is to pro vide a unitary construction in which all of 1 3, the working parts are mounted on a single insulator..

My invention will be readily understood with reference to the annexed drawings, wherein:

Figure l is a plan view of the unitary structure carrying the working parte of the instrument, without the casing or the scale, wird with one of the contact studs removed.

Figure 2 is a side elevatori of Figure 1, but with the scaie plate in position.

Figure 3 is a view of the back side of Fign gire l, the scale plate being shown in dotted Figure 4 is a side elevation of a linx-disn tributing member, or field spreader used in association with the magnet and armatureu Figure b is a plan view of an insulator used nto cover the magnetu Figure ti is a rear view oi the dial plateo 'In the diierent views, 1 is en insulator of strong material and referably one which is not susceptible to c anges in humidity or temperature. The insulator l is provided :with a slot 2 within which is pressed a permanent magnet 3. Lying flut on the dial side or the insulator l and directly over the magnet 3, is a plate 4, preferably oi? nonmagnetic material suchas brass. Passing through op* posits ends of the metallic plate 4, are a pair of studs 5, the right-hand one in Figure 1 being removed `to show a square hole 6 which is punched in the plate 4 to receive the square part of the stud to prevent the same from turning when the clamping nuts i are drawn up, Preferably a thin insulator 8, shown in p an view in Figure 5, is placed directly against the back of the insulator 1 to cover' the magnet 3 on the back side and also to hold it in position within the slot 2.

The plate 4 provided with an arm 9 which extends from the `body part of the plate'upwardly and inwardly over the plate. Between the arm 9 and the body portion of the plate 4, there is pivoted an armature 10 constructed in the manner shown in Mason Patent 1,680,465, issued on August 14, 1928. To this armature is fastened a pointer 11. The insulator l is provided with a pair of oppositely disposed notches 12 to receive iners 13 which extend from the iianges 14 armed on the side of the dial plate 15, which is also provided with a notch 16 to clear the armature 10 and the arm 9 as is clearly indicated in Figures 2 and 3.

In order to t a scale which is fairly uniform, I have Fund it necessary to use a device which acts as a spreader of the magnetic ux, and this field spreader preferabl takes the formof a soft iron strip 17 whic is positioned in a transverse direction across the magnet 3 and between it and the plate 4. The member 17- is thereby held in position by the plate 4 when the samer is clamped in position on the insulator 1.

It will be understood that when current plate 4, a magnetic field is set up which vin conjunction with the magnet 3, acts on the armature 10 to turn the same and lto give the indications on the scale 15. I have found that without the ux spreader above described, the scale divisions at the center, such as indicated in Figure 3, will be wider than at the ends but by using this device, I can obtain a su stantially uniform scale, only part of which is shown.

The iiux spreader 17 is preferably longer than the armature 10 and has an upturned end as shown in Figure 4, that engages the arm 9 -which then acts as a stop for the member 17, wherebyt can vonly be pushed inwardly to the point where lthe end 18 projects a short distance beyond the inner edge of the mag net 3.

Having thus described my invention, what I claim is:

l. An ammeter including an insulator hav-V ing a slot therein, a magnet positioned in said slot, a metallic plate overlying the magnet on one side of the insulator and held thereto by circuit connecting studs passing through the plate at opposite ends thereof, adjacent the ends of the magnet, an arm on the plate extending upwardly and inwardly thereoyer, an armature of magnetic material pivoted between said arm and the body part of said plate, a pointer carried by the armature, and

a scale plate carried by the insulator.

2. An ammeter having its working parts carried on a single insulator, said working parts comprising; a magnet set into the insulator, a metallic plate extending over the magnet on one side of the insulator, contact studs extending through opposite ends of the plate and the insulator and clamped thereto, an armature pivotally mounted on the plate, and a pointer moved by the armature.

3. An ammeter having its working parts carried on a single insulator, said working parts comprising; a magnet set into the insulator, a metallic plate extending over the magnet on one side of the insulator, contact studs extending through opposite ends of the plate and the insulator and clamped thereto, an armature pivotally mounted on the plate, a pointer moved by the armature, and a soft iron strip extending across the magnet and armature, but between the magnet and the plate and at right angles to the magnet.

4. An ammeter having its working parts carried on a single insulator, said working parts comprising; a magnet set into the insulator, a metallic plate extending over` the magnet on one side of the insulator, contact studs extending through opposite ends of the plate and the insulator and clamped thereto, an armature pivotall mounted on the late, a pointer carried y the armature, anfibi. fluxdistributor comprising a strip ofmmagnetic material held against the central-part of the magnet by said late, the strip being positioned transverse y ofthe magnet and extending beyond the magnet at one side thereof.

5. An ammeter having its working parts carried on a single insulator, said working arts comprising; a magnet set into the insuator and of substantially the same thickness as the insulator, a metallic plate lying fiat on one side of the insulator and extending Y over the magnet, Contact studs extending through opposite ends` of the plate and Y through the insulator and clamped thereto,

an arm integral with said plate, an armature pivoted between the arm and the body part of the plate, a pointer carried by the armature, and a flux-distributing member comprising; a strip of magnetic material extending at right ang es tothe magnet between the plate and magnet and beyond the magnet on one side thereof, said distributing member having an upturned end to engage said plate arm to limit the position of said member.

In testimony whereof, I aix my signature.

IVAR W. BROGGER. 

